Very few people use analog signal processing techniques these days.

It used to be common up until about 10-15 years ago, but then DSP's came along.

Now, you take a signal, buffer it by the minimuum amount necessary to get it into the DSP, and call it a day.

The best case is, you don't touch the signal at all, because any caps, filters, op amps can all distort the original signal.

You can do it all digitally, and it's much easier to modify on the fly if your technique isn't working well.

Boards and boards full of touchy analog electronics have been replaced by a single DSP.

And not many people are looking back.